Electrostatic precipitator



Oct. 29, 1963 E. M. BERLY ELECTROSTATIC PRECIPITATOR 3 Sheets-Sheet 1 Filed Feb. 16, 1960 m m w w.

ATTORNEYS Oct. 29, 1963 E. M. BERLY 3,108,865

ELECTROSTATIC PRECIPITATOR Filed Feb. 16, 1960 15 Sheets-Sheet 2 {I24 j I j IN VEN TOR.

no 5 l 104 ,FIG. 6 BY ATTO RNEYS Oct. 29, 1963 E. M. BERLY 3,108,865

ELECTROSTATIC PRECIPITATOR Filed Feb. 16, 1960 s Sheets-Sheet 3 IN V EN TOR.

FIG. 4 %M y%d4- ATTORNEYS United States Patent 3,108,865 ELECTROSTATIC PRECIPITATGR Edward M. Berly, 149 Christina St., Newton Highlands, Mass.

Filed Feb. 16, 1960, Ser. No. 8,971 3 Claims. (Cl. 55131).

The present invention relates to air cleaning by electrostatic precipitation and, more particularly to electrostatic precipitators of the type providing -(1) an inonizing zone in which entering air molecules are charged by a first electrostatic force and accumulate on dust particles that in consequence become charged and (2) a collecting zone in which the charged dust particles, under the direction of a second electrostatic force, are deposited on a suitable electrode component. The present invention contemplates a novel electrostatic precipitator having conventional high collection efliciency and low pressure drop but having a remarkably simple design that reduces component and fabrication costs and minimizes electrical and mechanical failure.

Primary objects of the present invention are: to provide an electrostatic precipitator of the foregoing type in which the ionizing zone and collecting zone are generated by elements of novel configuration supported and contained in a grounded casing that may be detached readily and safely for repair; in which the ionizing elements include plates that are supported and connected to the casing and wires that are tensioned between spring arms mounted on and insulated from the casing; and in which the collecting elements include a metallic mesh that is removably mounted in the casing.

Other objects of the present invention will in part be obvious and will in part appear hereinafter.

The invention accordingly comprises the apparatus possessing the features, properties and the relation of components, which are exemplified in the following de tailed disclosure, and the scope of which will be indicated in the appended claims.

For a fuller understanding of the nature and objects of the present invention, reference should be had to the following detailed description taken in connection with the accompanying drawings wherein:

FIGURE 1 is a perspective view of an electrostatic precipitator embodying the present invention;

A FIGURE 2 is another perspective view of the device of FIGURE 1;

FIGURE 3 is a cross-sectional view of the device of FIGURE 1, the section being taken along the lines 3-3 of FIGURE 1;

FIGURE 4 is an end view of one of the components of the device of FIGURE 1;

FIGURE 5 is a cross-sectional view of the device of FIGURE 1, the section being taken substantially along the lines 5-5 of FIGURE 1;

FIGURE 6 is a sectional view, partly broken away, taken substantially along the lines 66 of FIGURE 5; and

FIGURE 7 is an electrical schematic diagram of the electrical circuit of the device of FIGURE 1.

Generally, the illustrated embodiment of the present invention contemplates a housing that is rectangular in transverse cross-section having a forward open end through which air exhausted by a fan. Insertable into the rearward end of the housing is a casing which is composed of an electrically conducting metal to which ionizing plates are secured. Interspersed between the ionizing plates are tensioned wires that are supported by arms connected through insulators to the casing. Also connected to the casing is a metallic mesh that generates the collectzone through which air drawn into the housing by the fan through the ionizing region must pass. By virute of this simple construction, the electrical potential of the collector plates and the ionizer mesh are at the same potential.

With reference now to the drawings, a preferred embodiment of the present invention is disclosed in FIG- URES '1 and 2 as comprising a house 20, which supports and encloses the remaining mechanical and electrical components. The forward open end of housing 20 is covered by a panel 22 and a screen 24. The rearward open end of housing 20 is covered by a vented panel 26. In reference to FIGURES 3 and 5, the primary components of the apparatus include an inonizer 28, a collector 30 and a fan 33 for drawing air in sequence through the ionizer and the collector.

Collector 30 and ionizer 28 include elements which are mounted within a sheet metal conduit 32 of rectangular cross-section. As shown, conduit 32 includes an upper panel 36 having an upstanding flange 38, a lower panel 40 having a depending flange 42, a side panel 44 having an outward flange 46 and a side panel 48 having an outward flange 50. Outward flanges 46 and 50-, together with panel 26 are secured to perpendicular posts 52 and 54. These posts are afiixed to housing 10, by nuts 56, 56, which are turned onto screws 58, '58. Screws 53, 58 extend rearwardly from posts 52 and 54. Horizontal posts 60 and 62 cooperate with vertical posts 52 and 54 to position the flanges of conduit 34 and the contiguous portions of panel 26 securely together.

Extending between panels 44 and 48 are a stack of ionizer plates 64, 66 and 63. The ends of each of these plates are provided with depending extensions 7 0 that are spot Welded to panels 44 and 48 in order to secure the plates in predetermined positions. An array of high tension, high voltage ionizing wires 72, 74, 76 and 78 are mounted as follows. Extending inwardly from side panels 44 and 48 (FIGS. 3 and 4) are four insulating posts 80,

82, 84 and 86. To the inner free extremities of these posts are secured brackets 38, 90, and 94. Extending between the inner free extremities of brackets 88 and 92 is a vertical mounting strip 96 and extending between the inner free extremities of brackets'90, 94 is a vertical mounting strip 98. Mounting strips 96 and 98 carry a series ofobliquely extending spring arms 100* and 10-2, between which wires 72, 74, 76 and 78 extend. Ionizing wires 72, 74, 76 and 78 are at a potential of six to seven thousand volts for the purpose of low zone generation. These wires, preferably about six mils in diameter are composed of such a metal as tungsten or molybdenum. The spacing between the wires and the plates is approximately inch.

As is best shown in FIGURE 6, high voltage is applied to wires 72, 74, 76 and 78 from an insulated terminal 104 which extends from flange 38 and feeds the wires through a lead 106 and a lead 108. Lead 106 extends through a grommet 1'10. Associated with insulating post 104 is a conducting prod 112, which is connected to the high voltage leads 106 and 108 for the following purpose. Extending inwardly from panel 26 is a rod 114. Associated with rod 114 is a spring leaf 117 one end of which is connected to flange 38 of conduit 36 and the other end of which is biased toward conducting prod 112 of terminal 104. Normally, when panel 26 and conduit 36 are in operating position, spring leaf 117 is retained in its outermost position away from prod 112 by rod 114. However, when panel 26 is removed, rod 114 is withdrawn from contact with spring leaf 1 17 in such a way that spring leaf 117 contacts prod 112 in order to short the high potential of the voltage supply to ground and to protect the hands of an operator disassembling the apparatus.

Collector 30 includes a frame 116 of channel stock having inwardly directed flanges. Retained by these flanges are a pair of metallic webs 118 and 120, which and across the secondary of transformer 128.

in conjunction with the channel stock confines a metallic mesh 122. Mesh 122 is composed of conducting metallic fiber of sufiiciently large surface area to produce a distortion of the electrostatic field about a charged particle directed therethrough. By way of example, these fibers are composed of aluminum or stainless steel.

The electrical supply and control system is shown in FIGURE 7. In general, the power supply is a voltage doubler circuit energized by a high reaction transformer. Alternating current is applied through a pair of input leads 124-, .126 which energize the primary of a transformer 128 through a switch 131 and a variable resistor 132. A pilot light "134 and a motor 136 for the fan are connected in parallel across leads 124 and 126. Neglecting the small voltage drop across resistor 132, for example, an applied 115 volt cunrent is transformed to 3000 volts by tnansformer 128. Ideally the voltage across the secondary is a sine wave with a root mean square value of 3000 volts and a maximum of 4250 volts. When junction 133 is decreasing with respect to junction 14%, diode 14-2 is biased so that its anode is positive with respect to its cathode. Accordingly, cunrent flows through the diode, charging capacitor 144 so that junction 140 becomes positive with respect to junction 13 8. Capacitor 144 charges to the peak values of the sine wave. When the input voltage starts to decrease from its peak value, the cathode of diode 142 becomes more positive than its anode and the char-g ing current into the capacitor 144 ceases. The peak value of the voltage remains on capacitor .144 until bled ofi by leakage through the load resistance. However, it will be noted that the voltage across the diode 142. in the reverse direction is the sum of the voltages across capacitor 144 If there were no loss, a condition not the case in practice, the resulting voltage would equal peak-to-peak value of the incoming sine wave. A second diode and a second capacitor 1'50 are connected across diode 142. Second diode 148 conducts, charging capacitor 150 as soon as its anode is positive with respect to its cathode. The driving voltage for this circuit is the sum of the voltages across capaci tor 144 and the secondary of transformer 128.

In practice, provision is made to limit any transient currents that may occur when either the collector or the ionizer flashes over. Two types of limiting are employed in this power supply: reactive limiting by the use of a transformer with a large amount of leakage reactance between the primary and secondary; and resistive limiting by use of resistor v132i to damp out any oscillations produced between the leakage reactance and the circuit capacitors. The output voltage is reduced from the peak to peak value of the transformer secondary voltage by the action of the charging currents flowing through the limiting impedance. The output voltage of this power supply is 62.00 volts DC. when 250 microamps are flowing in the ionizer load.

In operation, containing particulate matter enters ionizer 28 where the particles become charged positively or negatively by ions produced in a corona discharge. The charged particles then pass to the collector 30 where they are deposited. The precipitation of these particles onto the conductive fibres results firom the electrostatic field that surrounds the charged particles. The field lines about the particles terminate on the metal fibres and the particles are drawn to the fibres under the influence of their own fields. The fibres tend to concentrate the field lines in such a way as to enhance their strength.

Since certain changes may be made in the above apparatus without departing from the scope of the invention herein involved, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted in an illustrative and not in a limiting sense.

What is claimed is:

1. An electrostatic precipitator comprising a housing composed of an electrically insulating materiahsaid housing providing an entrance region and an exit region, a conduit composed of an electrically conducting material, said conduit providing an entrance region and an exit region, said conduit being within said housing, said entrance region of said conduit and said exit region of saidconduit being aligned with said entrance region of said housing and said exit region of said housing respectively, a plurality of ionizing wires and conducting plates disposed on said conduit at a first location and a conducting mesh disposed on said conduit at a second location, said first location and said second location being sequenced from the entrance region of said conduit toward the exit region of said conduit, the extremities of said plates being connected to said conduit, a plurality of insulators carried on said conduit between said first location and said second location, pairs of insulators on opposite sides of said conduit pairs of spring arms carried by said pairs of insulators, said ionizing wires being tensioned between said spring arms, means in said housing for drawing air through the said entrance region or" said conduit and from said exit region of said conduit, means for establishing said conduit, said mesh and said plates at ground potential, means for establishing said wires at a potential removed firomground.

2. The electrostatic precipitator of claim 1 wherein said mesh is metallic.

3. The electrostatic precipitator of claim 1 comprising, additionally, an insulating post secured to said housing, a conducting terminal on said insulating post, said source of potential being applied to said conducting terminal, said ionizing wires being electrically connected to said terminal, a spring element on said housing biased toward said terminal, said spring element being grounded, a screen at the entrance region of said conduit, means projecting from.

said screen for maintaining said spring element at a distance from said terminal when said screen is in position at said entrance region and for permitting said spring element to contact said terminal when said screen is removed from said entrance region.

References (Iited in the file of this patent UNITED STATES PATENTS 2,579,441 Palmer Dec. 18, 1951' 2,721,622 Ditzler Oct. 25, 1955 2,780,305 Bonatz Feb. 5, 1957 2,900,042 Coolidge a in Aug. 18, 1959 2,933,151 Kurtz Apr. 19, 1960 2,979,155 Vlier Apr. 11, 1961 

1. AN ELECTROSTATIC PRECIPITATOR COMPRISING A HOUSING COMPOSED OF AN ELECTRICALLY INSULATING MATERIAL, SAID HOUSING PROVIDING AN ENTRANCE REGION AND AN EXIT REGION, A CONDUIT COMPOSED OF AN ELECTRICALLY CONDUCTING MATERIAL, SAID CONDUIT PROVIDING AN ENTRANCE REGION AND AN EXIT REGION, SAID CONDUIT BEING WITHIN SAID HOUSING, SAID ENTRANCE REGION OF SAID CONDUIT AND SAID EXIT REGION OF SAID CONDUIT BEING ALIGNED WITH SAID ENTRANCE REGION OF SAID HOUSING AND SAID EXIT REGION OF SAID HOUSING RESPECTIVELY, A PLURALITY OF IONIZING WIRES AND CONDUCTING PLATES DISPOSED ON SAID CONDUIT AT A FIRST LOCATION AND A CONDUCTING MESH DISPOSED ON SAID CONDUIT AT A SECOND LOCATION, SAID FIRST LOCATION AND SAID SECOND LOCATION BEING SEQUENCED FROM THE ENTRANCE REGION OF SAID CONDUIT TOWARD THE EXIT REGION OF SAID CONDUIT, THE EXTREMITIES OF SAID PLATES BEING CONNECTED TO SAID CONDUIT, A PLURALITY OF INSULATORS CARRIED ON SAID CONDUIT BETWEEN SAID FIRST LOCATION AND SAID SECOND LOCATION, PAIRS OF INSULATORS ON OPPOSITE SIDES OF SAID CONDUIT PAIRS OF SPRING ARMS CARRIED BY SAID PAIRS OF INSULATORS, SAID IONIZING WIRES BEING TENSIONED BETWEEN SAID SPRING ARMS, MEANS IN SAID HOUSING FOR DRAWING AIR THROUGH THE SAID ENTRANCE REGION OF SAID CONDUIT AND FROM SAID EXIT REGION OF SAID CONDUIT, MEANS FOR ESTABLISHING SAID CONDUIT, SAID MESH AND SAID PLATES AT GROUND POTENTIAL, MEANS FOR ESTABLISHING SAID WIRES AT A POTENTIAL REMOVED FROM GROUND. 